Electric method of fusion.



N0. 685,043. Patented Oct. 22, |90I. W. T. GIBBS.

ELECTRIC METHOD 0F FUSION.

(Application filed Mar. 15, 1901.1

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UNITED STATES PATENT FETCE.

WILLIAM T. GIBBS, OF BUCKINGIIAM, CANADA.

ELECTRIC METHOD OF FUSION;l

SPECIFICATION forming part of Letters Patent No. 68 5,043, dated October22, 1901.

@riginal application led October 14, 1897, Serial No. 655,111. Dividedand this application led March 15, 1901. erial No. 51,304. (Nospecimens.)

`many, No. 107,736, dated February 4.-, 1898,

and Great Britain, No. 4,819, dated February 26, 1898.

My invention relates to methods of fusion for the reduction of mineralsand analogous purposes, the general object of the invention being toavoid the difficulties existing with present electric methods of fusionand to provide a method of more general application than those now inuse.

In electric methods of fusion it has heretofore been thought necessaryto either use an 'arc or to pass the current throughthe material itselfor through a high-resistance medium placed in immediate contact with thematerial.

Apart from the economical objections to the use of the arc and theconstant manual regulation of the carbons required methods of electricfusion employing thearc are inapplicable or very objectionable inmanycases on account of the continuous destruction of the carbons, whichdistributes carbon-dust throughout the product of the furnace, so as tomake a pure product impossible, and because the arc is accompanied byextremely high local temperatures, much higher than is required for anysmelting operation and productive of injurious resulta, In many casesalso the vapor of carbon which is given off injures the product in thesame way as the carbon-dust. In smelting some metals also-as, forinstance, Zincit is impossible to obtain an arc owing to the conductiveYproperties of the vapor of the metal, so that no method of electricfusion employing an are can be used. When the current is passed througha high-resistance medium placed in immediate contact with the material,that medium is sometimes in a granular form and sometimes in the shapeof a comparatively small rod. In methods of fusion in which a granularliiglrresistance mass is placed in contact with the material to bereduced the contact of the material with the incandescent carbon causesmore or less oxidation of the carbon and consequent diffusion of thecarbon through the material reduced, interfering in this manner, as inthe case of the arc, with the purity of the prod uct. Again, the currentin passing from one portion to another of a granular mass makes a largenumber of small arcs which have the same effect in the formation ofcarbon dust and vapor and of an injuriously high local temperature as asingle large arc. The conconstant attention of an operator is requiredalso to secure practical results, because owing to the change inposition of the granular particles the resistance of the mass of carbonis continually varying, requiring constant attention to the regulationof the current, satisfactory results in such processes, therefore,depending upon skill and constant attention. Such methods also are notapplicable in many cases in which it is not practical to bring theincandescent material into contact with the articles to be heated.

Vhen the high-resistance medium through which the current is passed isin the shape of a comparatively small carbon rod placed in immediatecontact with the material to be treated, the carbonrod merely furnishesa path for the current at the beginning of the smelting operation and isthen destroyed and replaced by an arc, or else the current then passesthrough the molten material itself. This method involves most of thedisadvantages incident to both the processes above referred to. When thecurrent passes through the material itself also, the resistance will becontinually varying with the ebullition of the molten mass, the circuitat times being intercepted by large quantities of gas and at timestraversing a nearly continuous path through molten material, so that theprocess is subject to great irregularity. Moreover, a process in whichthe current is passed through the material itself is of course notgenerally applicable, since most metals have too high a IOO degree ofconductivity, and its use is limited to those materials which have arelatively high resistance.

My invention consists of a process in which the heat is developed by thepassage of the current through acontinuous high-resistance medium, as acarbon rod, in a closed furnace and out of contact with the material tobe treated. The heat is transmitted from the conductor to the materialunder treatment directly by radiation and reilection without theinterposition of any substance between the material treated and theconductor.

In the drawings annexed, forming a part of this specification, Figure 1is a vertical section of the furnace adapted for use in carrying outI myprocess, and Fig. 2 is a plan'view of a modification which may be usedfor larger furnaces.

Referring to said drawings, the furnace A is a chamber built of anysuitable refractory materiahas fire-brick or carbon,having, preferably,an arched roof, although this is not essential to the furnace. Thecurrent is preferably introduced to the furnace through the conductors CC, which connect with carbon blocks or abutments B, between which ex.

tends the resistance-rod D. The material E to be treated rests upon thebottom of the chamber and may be introduced through the inletpipe F andthe fused material may be drawn off through the exit G. II is anoutlet-pipe for the escape of gas and, in case of a volatileproduct,fondrawing off the product. The blocks B may be fix-ed in thefurnace in any suitable manner. I find' a goodconstruction to be theinsertion of the blocks i-n the iron sockets K.

It is an advantage of my process that a furnace can be built to. utilizealmost any desired amount of power in carrying it out. This may be doneby providingT the furnace with a numberI of resist-ance-conducters andpassing the current in series through them, as shown in diagram in Fig.2, in which a furnace is illustrated contain-ing three sets ofabutments, the current passing in succession through each. This isimpracticable where arcs are employed, since itis not feasible tooperate arcs in series in the case of afurnace.

By the use of my process the diiiculties existing with prior electricmethods of fusion are avoided. The material` to be fused can be whollypreserved from contact with carbon and carbon-vapor, andit has verynumerous advantages over the processesin common use which have beendescribed above. The carbon resistance beingout of contact with thematerial to be reduced at all times, both when said material is in solidand fused condition, and not being subject to material disintegration bythe action of the current, as in the ease of the arc, the material to bereduced is not subjected either to carbondnst or carbon-vapor, and theprocess is con#- eontinuous instead of being intermittent, as

f done in metallurgical operations.

it is where an are is the source of heat. There' are no local extremelyhigh temperatures, as in the case of the are, but a substantiallyuniform and adjusted temperature is secured, which is subject toabsolute regulation from the lowest to the highest temperatures, and theprocess is not dependent upon the con stant attention of an operator, asthe flow of the current is constant and uniform, except as variationsare introduced by changing the adjustment. It will be Observed also thatmy process may be used where a process in volving the use of an arcwould be wholly impracticable on account of the impossibility ofobtaining an arc, as in the case of zinc. The action of the heat is uponall the material being treated instead upon only a. porA tion of thematerial, as is the case where the incandescent conductor is placed inthe material to be reduced, and my process need not be interrupted forthe introduction of new material or the removal of the reduced prod; uctor of slag until .such time as is desired.

There have been suggested heaters or ovens in which the conductors areplaced in the sides or walls of the chamber which holds the material tobe reduced. These conductors have usually been of metal. Ovens orheaters of this construction are not adapted, and, so far as I am aware,their use has not been attempted for metallurgical operations, since thedegree of heat which they are capable of developing is not suitabletherefor. I am aware that suggestions have been made that heaters ofsuch construction could be used as furnaces, but I know that this couldnot be Moreover,

even if a sufficiently high degree of heat could be developed thereinfor metallurgical purposes the material treated when fused would comeinto contact with the cond u ctor, producing oxidation, contaminatingthe material under treatment, and in some instances shortcircuiting thecurrent, thereby rendering the process impracticable. In some cases ithas been proposed to inclose the material being treated in such a heaterin a crucible placed between the material under treatment and theconductor. The interposition of the crueiblo f would of course Vcr"Tgreatly reduce the amount of heat available, and for this reason i also,as well as on account of the contamina-- tion of the material undertreatment by contact with the carbon of the crucible, a processemploying such a construction of heater could not be employed formetallurgical operations.

By continuous co11duetoi"l1ercin I mean such a conductor that thecurrent ilows through the same without any interruption such as would beproduced bythe separation of two portions of the conductor after the manner of the carbon rods in an electric-arclamp.

This application forms a division of my application Serial No. 655,111,filed October' 14:,

j issn W hat I claim is I IOO rrd

1o interposition of any substance between the l material treated and theconductor, substani tially as described.

In testimony whereof I have hereunto set my hand in the presence of twosubscribing witnesses.

WVILLIAM T. GIBBS.

Witnesses:

C. J. SAWYER, A. A. V. BOURKE.

